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| question,option1,option2,option3,option4,answer,difficulty | |
| What is the size of an int in Java?,2 bytes,4 bytes,8 bytes,16 bytes,4 bytes,low | |
| Which keyword is used to create a class in Java?,class,Class,new,create,class,low | |
| What is the default value of a boolean variable?,true,false,null,undefined,false,low | |
| Which method is used to print output in Java?,println(),display(),output(),print(),println(),low | |
| What does JVM stand for?,Java Virtual Machine,Java Virtual Model,Java Verified Machine,Java View Model,Java Virtual Machine,low | |
| Which operator is used for comparison in Java?,=,==,!=,<>,==,low | |
| What is the entry point of a Java program?,main(),start(),run(),execute(),main(),low | |
| What is the extension of compiled Java files?,.java,.class,.exe,.javac,.class,low | |
| Which package is imported by default in Java?,java.util,java.lang,java.io,java.net,java.lang,low | |
| Which keyword is used to inherit a class in Java?,extend,extends,inherit,inherits,extends,low | |
| What is used to handle exceptions in Java?,try-catch,if-else,for loop,while loop,try-catch,low | |
| Which of these is a reserved keyword in Java?,void,main,static,return,void,low | |
| What does the 'final' keyword do?,Creates a constant variable,Creates a variable,Creates a loop,Creates a method,Creates a constant variable,low | |
| Which data type is used to store a sequence of characters?,int,char,String,double,String,low | |
| Which method is used to convert a string to lowercase?,toLowerCase(),toLower(),convertLower(),makeLowerCase(),toLowerCase(),low | |
| What is the parent class of all classes in Java?,String,Object,Class,BaseClass,Object,low | |
| What is the default value of an int variable?,0,-1,null,undefined,0,low | |
| Which loop is used to iterate a fixed number of times?,for,while,do-while,foreach,for,low | |
| Which access modifier allows visibility within the same package?,public,protected,default,private,default,low | |
| What is the output of '5 + 2 + \"3\"' in Java?,10,523,73,Error,73,medium | |
| Which interface is implemented for multithreading in Java?,Runnable,Thread,Callable,MultiThread,Runnable,medium | |
| How do you define a constant in Java?,const,final,static,define,final,medium | |
| Which exception is thrown when a thread is waiting or sleeping?,InterruptedException,IOException,NullPointerException,RuntimeException,InterruptedException,medium | |
| Which method is used to stop a thread?,stop(),terminate(),shutdown(),halt(),stop(),medium | |
| How are elements stored in a TreeSet?,Insertion order,Sorted order,Random order,Reverse order,Sorted order,medium | |
| Which class is used for buffered input in Java?,BufferedReader,InputStreamReader,Scanner,FileReader,BufferedReader,medium | |
| How do you serialize an object in Java?,By using Serializable interface,By using Externalizable interface,By using ObjectOutputStream,All of the above,All of the above,medium | |
| What is the purpose of 'super' keyword in Java?,Access parent class methods,Access parent class constructor,Access parent class variables,All of the above,All of the above,medium | |
| What is the default priority of a thread?,5,1,10,0,5,medium | |
| Which method is called when an object is garbage collected?,finalize(),dispose(),clear(),delete(),finalize(),medium | |
| Which of these are checked exceptions?,IOException,NullPointerException,ArrayIndexOutOfBoundsException,ArithmeticException,IOException,medium | |
| What is the return type of 'compareTo()' method?,int,boolean,String,void,int,medium | |
| Which method is used to compare two strings ignoring case?,compareTo(),compareToIgnoreCase(),equals(),equalsIgnoreCase(),compareToIgnoreCase(),medium | |
| What is the result of '10 << 2'?,20,40,30,10,40,medium | |
| What happens when you divide an integer by zero?,ArithmeticException,NullPointerException,Infinity,NaN,ArithmeticException,medium | |
| How do you create an unmodifiable collection?,Collections.unmodifiableCollection(),Collections.immutableCollection(),Collections.staticCollection(),Collections.readOnlyCollection(),Collections.unmodifiableCollection(),medium | |
| Which collection allows null values?,ArrayList,HashMap,HashSet,All of the above,All of the above,medium | |
| What is the time complexity of accessing an element in HashMap?,O(1),O(n),O(log n),O(n log n),O(1),medium | |
| Which stream is used for reading binary data?,InputStream,BufferedInputStream,FileInputStream,All of the above,All of the above,medium | |
| What is the result of 'Math.floor(-2.5)?',-3.0,-2.0,2.5,-2.5,-3.0,high | |
| How can you make a method synchronized in Java?,Use the synchronized keyword,Use the lock() method,Use the thread-safe interface,Use the sync block,Use the synchronized keyword,high | |
| What is the purpose of 'volatile' keyword?,Ensures visibility of changes across threads,Prevents thread execution,Marks a variable as constant,Prevents garbage collection,Ensures visibility of changes across threads,high | |
| What is the difference between '==' and 'equals()'?,'==' checks reference equality, 'equals()' checks content equality,'==' checks content equality, 'equals()' checks reference equality,Both are the same,Depends on implementation,'==' checks reference equality, 'equals()' checks content equality,high | |
| Which design pattern is used by Java's runtime class?,Singleton,Prototype,Factory,Adapter,Singleton,high | |
| What happens if a thread is interrupted while sleeping?,Throws InterruptedException,Continues sleeping,Ignores interruption,Terminates immediately,Throws InterruptedException,high | |
| Which Java feature prevents modification of an object's state?,Immutability,Encapsulation,Abstraction,Polymorphism,Immutability,high | |
| What is the output of 'System.out.println(10 + 20 + \"30\");'?,30,1030,2030,Error,1030,high | |
| What does 'strictfp' modifier do?,Restricts floating-point calculations,Enables faster floating-point operations,Makes floating-point consistent,None of the above,Restricts floating-point calculations,high | |
| Which Java feature allows runtime method resolution?,Polymorphism,Abstraction,Encapsulation,Inheritance,Polymorphism,high | |
| What is a marker interface?,Interface with no methods,Interface with default methods,Interface with a single method,Interface with static methods,Interface with no methods,high | |
| What is the purpose of 'ClassLoader' in Java?,Loads classes at runtime,Compiles classes,Links classes,Stores class metadata,Loads classes at runtime,high | |
| How can you avoid deadlocks in Java?,Avoid nested locks,Use try-finally for locks,Use a timeout for locks,All of the above,All of the above,high | |
| What is the result of 'Integer.parseInt(\"10\") + Integer.valueOf(\"20\")'?,1020,30,10,Error,30,high | |
| How can you make an object eligible for garbage collection?,Set its reference to null,Call System.gc(),Remove all references,All of the above,All of the above,high | |
| What is the default encoding for Java strings?,UTF-8,UTF-16,ASCII,ISO-8859-1,UTF-16,high | |
| Which thread state indicates it is eligible to run but not running?,RUNNABLE,BLOCKED,WAITING,TERMINATED,RUNNABLE,high | |
| What is the role of 'transient' keyword?,Prevents serialization,Ensures serialization,Excludes field during serialization,Includes static fields,Excludes field during serialization,high | |
| What is the result of '0.1 + 0.2' in Java?,0.3,0.30000000000000004,0.2,Error,0.30000000000000004,high | |
| How does 'HashMap' handle hash collisions?,Separate chaining,Linear probing,Open addressing,Rehashing,Separate chaining,high |